Acrylonitrile is the basis for a family of important commercial polymers. For example, copolymers of butadiene with less than 50% acrylonitrile provide oil resistant polymers. Copolymers of alkyl acrylates with acrylonitrile provide a range of polymer products. For example, when ethyl acrylate is the major component, oil elastomers are obtained; and when acrylonitrile is the predominant comonomer, useful molded plastic materials are obtained. Copolymers of a major proportion of styrene and minor proportions of acrylonitrile are also useful in modifying vinyl chloride polymers, as moldable plastics and as components as ABS resin blends. Normally, these acrylonitrile containing polymers are prepared by polymerization in water. Even when such polymerizations are substantially complete, there still remains an undesirable amount of unpolymerized acrylonitrile dissolved both in the polymer and the water on the order of several thousand to several hundred parts per million. Normal procedures of stripping by vacuum or steam do not remove all of this undesirable acrylonitrile.
On the basis of animal and human epidemiological data, OSHA has determined that exposure to the volatile and highly toxic acrylonitrile poses a potential carcinogenic risk to humans. In order to minimize employee exposure risks to acrylonitrile, a limit of 2 ppm of acrylonitrile in the air, averaged over eight hours, has been imposed. It has been discovered that the limit of 2 ppm acrylonitrile in air can be achieved and maintained by reducing content of the acrylonitrile monomer in the latex, bulk polymer or waste water containing same to less than about 100 ppm.